This invention pertains to methods and apparatus for using the polarity reversals of a confined plasma, or similar electrode on one side of a dielectric, to generate useful ions and ionized molecules with a plasma around an electrode external to the confining dielectric, thus, being a plasma Ion Source; and a method and apparatus for the separation of these ions and molecules according to their polarity by use of an electric field; and a method and apparatus to couple or make available the selected polarity of the separated ions and molecules to a detection system. Thus, these Coupled Ionization Apparatus and Methods provide a novel ionizer and the techniques for interfacing the ionizer to chemical detection systems. Among detection systems that could be attached to and use this ion generator are, but not limited to: Ion Mobility Spectrometer [IMS]; Ion Barrier Mobility Spectrometer [IBMS]; ion capture smoke/particle detector; Particle Mobility Spectrometer; ion or particle differential mobility analyzer using DC electric fields; ion or particle differential mobility analyzer using asymmetrical radio frequency [RF] fields, and; reduced pressure mass detectors, such as a Mass Spectrometer.
One of the objectives of this novel ionization technique is to suppress point-to-point corona ionization. Its purpose is to minimize direct streamers normally generated by conventional point-to-plane corona discharge ionization sources and increase the quantity of pre-arc glow discharge ionization. It is similar to corona but without the corona point erosion and instability leading to a short ion source lifetime. Only the quantity of ions that will satisfy the required system signal-to-noise ratio should be generated using this technique. As the energy to the plasma ion source is increased, the ions generated outside the dielectric also increase in numbers, and they become more energetic. At very high ion source energy levels more corona and less glow discharge will occur and negative ions of ozone (O3—) and nitrous oxides (NOX—) will be produced. Also, when an electrode is separated from the dielectric, corona can occur. There are no apparent changes in the ions produced in the positive mode. This is typical of corona ionization.
It is an object of this invention to replace point-to-point corona discharge by an ion source that includes design configuration flexibility.
It is another object of this invention to replace point-to-point corona discharge by an ion source that includes dimensional stability.
It is yet another object of this invention to replace point-to-point corona discharge by an ion source that includes simplicity and ruggedness of design.
It is yet a further object of this invention to replace point-to-point corona discharge by an ion source that includes extended source lifetime.
More objects of the invention will become apparent to professionals in the chemical and biological defense, law enforcement, health monitoring, disease control, industrial safety and hygiene, environmental, chemical, metallurgical, and related areas following perusal of the complete specification